Accounting for Regional Aquifer Data in a Simulation Model of the Burgan Minagish Reservoir – A New Approach

Abstract

Abstract Burgan Minagish (BGMN) reservoir in the Greater Burgan field, is one of the reservoirs among others that has been producing from Minagish formation. It has been in production intermittently since 1960's though full development was delayed due to high H2S content and the need to construct sour processing surface facilities. The analysis of reservoir pressure over time indicated that the main reason of reservoir pressure decline in BGMN was production from three neighboring reservoirs producing from the same formation. This was clear as pressure decline continued for the period of 2005-2009 while Burgan-Minagish was not in production. Reservoir pressure dropped below bubble point in 2011 and made it necessary to design and implement a pressure maintenance program. This included a water injection scheme which has been implemented since 2018. In 2012, using a novel approach (Al-Faresi et al, 2012), two Fast and Slow Loop simulation models were built to model a regional aquifer and quantify flux exchange between Burgan-Minagish, regional aquifer and surrounding reservoirs. While the Fast Loop coarse model was used to match field level production and pressure data, the detailed BGMN Slow Loop model would solely focus on modeling of BGMN having incorporated the impact of neighboring reservoirs via calculated flux derived from Fast Loop model. The drawback, however, is that every time the model needs updating, a tedious and manual process must be performed to calculate flux rate across the BGMN boundaries from the Fast Loop and then incorporate it explicitly into the Slow Loop model. 10 years after the previous study, a new approach for regional aquifer modeling has been utilized to integrate two existing simulation models in a combined one that serves for both purpose of modeling the regional aquifer and surrounding reservoirs as well as history matching of high resolution BGMN model. The history matched combined model has been used to extensively evaluate BGMN reservoir production performance under different development scenarios. We have compared the results with existing two-model solution, and it is clear from the analysis that the impact of neighboring reservoirs as well as the regional aquifer is captured in the new approach. The novelty of the new approach is that it allows a seamless interaction between three surrounding reservoirs with BGMN. The unified simulation model is more convenient to use and eliminates the manual work of influx calculations. It is also more flexible and repeatable as systematic updates on both static and dynamic modeling sides for any reservoir in the area of interest could be easily implemented.